R v Sim

R. v. Sim

[1988] O.J. No. 2250
Ontario Court of Appeal — Robins, Tarnopolsky and Finlayson JJ.A. | October 11, 1988

Background

Dwight Donald Sim was charged with speeding after a police officer used radar to measure his vehicle's speed. At trial, Sim argued that the Crown had failed to establish a proper case because they didn't prove the radar device was actually capable of accurately measuring vehicle speeds. The justice of the peace convicted Sim anyway, and he appealed to the Ontario Court of Appeal.

This case was part of a larger legal battle in the 1980s over what the Crown needed to prove to use radar evidence in speeding prosecutions. Some defendants were arguing that it wasn't enough for police to just test the radar — they had to prove the device itself was scientifically capable of accurate speed measurement.

Issues

1. Must the Crown prove that a radar device is capable of accurately measuring vehicle speeds?
2. What evidence is required to establish a prima facie case for speeding based on radar?

The Radar Evidence Requirements

The Court of Appeal firmly rejected Sim's argument in a brief but decisive ruling. The court found that the Crown had presented sufficient evidence because: (1) the police officer tested the radar unit both before and after measuring Sim's speed, and (2) there was evidence showing the officer was familiar with the radar unit and knew how to use it properly.

The court explicitly stated they could find "no error in law on the part of the justice of the peace." This ruling aligned Ontario law with the practical reality that police officers aren't radar engineers — they just need to know how to operate the equipment and verify it's working correctly through testing procedures.

The Sim decision effectively shut down a line of defence arguments that had been gaining traction in other provinces, particularly Alberta, where courts had required more extensive proof of radar accuracy. Ontario took a more streamlined approach, focusing on proper testing and operator competence rather than abstract scientific capabilities.

Key Takeaway

Testing the radar before and after your speed measurement, plus officer familiarity with the device, is enough for the Crown to prove their speeding case.

Don't expect to beat a radar ticket by arguing the Crown needs to prove the scientific accuracy of radar technology itself. Focus instead on whether the officer actually performed the required tests or was properly trained on the specific device used.